Transdermal delivery of drugs is achieved by a number of technologies including high velocity particles, hydration, chemical enhancement, iontophoresis, ultrasound, and microneedle arrays (μarrays). In general, microneedles are defined as needles having lengths in the range of 1-1000 micrometers (μm). Microneedles are designed to penetrate the outer layer of the epidermis in such a manner as to not compromise the underlying nerves and blood vessels of the dermal layer. In this manner, microneedles are an effective way of administering both small and large molecule drugs without causing pain or bleeding. When microneedles are assembled in a pattern, such as in an array, they are an effective way to breech a substantial surface area of the epidermis in a minimally invasive way.
In view of the foregoing, it can be appreciated that μarrays have the potential to be integrated in a delivery device that can be reliably used by a patient without the oversight of a healthcare professional. By way of example, transdermal delivery has the ability to elicit a favorable immune reaction in response to vaccines since the point of delivery is ripe with molecules involved in the immune response. It has been found that by delivering DNA directly into the intracellular compartment via a transdermal delivery process, approximately 1,000 times less DNA may be used than conventional needle and syringe delivery to achieve a comparable response. However, the transdermal delivery process is based on the high velocity approach to transdermal delivery. This approach requires a bulky device for purposes of administration and microscopic gold particles to be coated with the DNA plasmid to act as a carrier. Currently, all commercial μarray efforts use either a drug coated onto the surface of the μarray or are constructed of a biodegradable polymer infused with a drug. Both embodiments limit the maximum dose that may be delivered by the μarray. In addition, both of these prior μarrays require pharmaceuticals to be reformulated, thereby adding substantial development and regulatory costs to μarrays. As a result, the use of μarrays is not a delivery option for many drugs. Hence, a μarray that could administer a drug without the need of a coated carrier particle and has the advantage of being housed in a small, disposable device would be highly desirable.
Therefore, it is a primary object and feature of the present invention to provide an active microneedle array designed to penetrate the outer layer of the epidermis and subsequently create and maintain a sufficiently sized hole to allow fluid flow past the outer layer.
It is a further object and feature of the present invention to provide an active microneedle array designed to penetrate the outer layer of the epidermis that allows for the administration of a drug.
It is a still further object and feature of the present invention to provide an active microneedle array designed to penetrate the outer layer of the epidermis that may be housed in a small, disposable device.
It is a still further object and feature of the present invention to provide an active microneedle array designed to penetrate the outer layer of the epidermis that is simple to use and inexpensive to manufacture.
In accordance with the present invention, an active microneedle array is provided for penetrating the outer layer of the epidermis. The active microneedle array includes a base having first and second sides. The first side of the base is engageable with the epidermis. A microneedle projects from the first side of the base, The microneedle is moveable between a first initial configuration and a second deformed configuration in response to engagement with the epidermis so as to form an opening therein.
The microneedle is free of coatings and is defined by first and second flexible sidewalls. Each sidewall includes an inner surface partially defining a flowpath therebetween. In a first embodiment, the sidewalls are generally parallel to each other in a spaced relationship with the microneedle in the initial configuration. The sidewalls engage each other with the microneedle in the deformed configuration. The base includes an aperture extending between the first and second sides thereof. The aperture is positioned adjacent the microneedle.
In accordance with a further aspect of the present invention, an active microneedle array is provided for penetrating an outer layer of the epidermis. The active microneedle array includes a base having first and second sides. The first side is engageable with the epidermis. A microneedle projects from the first side of the base. The microneedle is moveable between a first initial configuration and a second deformed configuration. An aperture extends between the first and second sides of the base. The aperture is positioned adjacent the microneedle. The microneedle is urged to the deformed configuration in response to engagement with the epidermis so as to form a passageway in the outer layer of the epidermis.
The microneedle is free of coatings and, in a first embodiment, the microneedle is defined by first and second flexible sidewalls. Each sidewall includes an inner surface partially defining a flowpath therebetween. The sidewalls are generally parallel to each other in a spaced relationship with the microneedle in the initial configuration. The sidewalls engage each other with the microneedle in the deformed configuration. The aperture may be positioned between the first and second sidewalls. Alternatively, the microneedle may extend along an axis in the initial configuration. The microneedle may twist about the axis to move to the deformed configuration.
In accordance with a still further aspect of the present invention, a method of penetrating an outer layer of an epidermis is provided. The method includes the steps of providing a microneedle array having a base and microneedle projecting therefrom. The microneedle has an initial configuration. The epidermis is penetrated with the microneedle such that the microneedle deforms to a deformed configuration and creates a passageway in the outer layer of the epidermis.
The step of penetrating the epidermis with the microneedle may include the additional step of twisting the microneedle from the initial configuration to the deformed configuration. Alternatively, the microneedle may be defined by first and second flexible sidewalls. The sidewalls are generally parallel to each other in a spaced relationship with the microneedle in the initial configuration. With the microneedle in the deformed configuration, the sidewalls engage each other. It is contemplated to provide an aperture through the base. The aperture through the base may be position at a location between the first and second sidewalls or at a location adjacent the microneedle.